Microwave-assisted cation exchange toward synthesis of near-infrared emitting PbS/CdS core/shell quantum dots with significantly improved quantum yields through a uniform growth path.

In this study, we develop a reproducible and controllable microwave-assisted cation exchange approach, for the first time, to quickly synthesize high-quality, near-infrared emitting PbS/CdS core/shell quantum dots (QDs). These monodisperse QDs, emitting in the range of 1300-1600 nm, show a quantum yield as high as 57% that is ~1.4 times higher than that achieved by the same QDs prepared using conventional heating in an oil bath. To the best of our knowledge, it is the highest reproducible value reported to date for PbS-based QDs in this emission range. More importantly, the as-synthesized PbS/CdS QDs can self-assemble nearly perfectly and easily at the micrometer scale as a result of their uniform shape and narrow size distribution.